Thermal effects of currents, short circuits
Thermal effects of currents
Definition: when the current passes through the conductor, the electrical energy is constantly converted to thermal energy as a result of the collision of free electronics. The current passes through the conductor with heat, known as the heat effect of the current.
The conversion of electricity to heat is calculated as
Q is the heat produced by the conductor, w is the energy consumed.
Short circuit
Definition: power leads to two lines of load, which are not directly connected by overload. It's called short circuits.
Short circuit analysis: retardation (r) smaller, current (i) larger, expressed in formulae
(a) the hazards of short circuits: rising temperatures, burning equipment, fires; it's generating a lot of power, burning power, breaking the grid.
Protective measures: installation of automatic switches; installation of smelters.
Connectivity of circuits (serial, conjunctive, mixed)
Serial circuits
The resistance chain connects the end of the resistance in turn, but the current only connects by one route.
Circuit chains are characterized by the same current as total currents, i = i1 = i2 = i3..
The total voltage is equal to the sum of the resistance voltages, i. E. U = u1 + u2 + u3..
Total electrical resistance equals load resistance sum, i. E. R = r1 + r2 + r3..
The ratio of voltage reduction to each electrical resistance equals the ratio of resistance, i. E
It's..
Power chain: connect the negative pole of the previous power to the positive extreme of the latter.
Characteristics: access to large voltage and power.
The formula is:
E = e1 + e2 + e3 +... + en
R0 = r01 + r02 + r03 +... + r0n
And connect the circuits
The combination of resistance: connecting several of the circuits together, called resistance.
Characteristics of combined circuits: equal voltage at each end of the resistance, i. E. U1 = u2 = u3 = ... = un;
The total current of the circuit is equal to the sum of the current of the circuits, i. E. I = i1 + i2 + i3 + ... + in;
The bottom of total circuit resistance r is equal to the bottom of all circuits, i. E
And the more the load, the smaller the total electrical resistance, the greater the current supply, the heavier the load.
The currents of the roads are inversely proportional to their respective electrical resistance, i. E
Power interface: connect all the positive poles of power to the positive poles of power, connect all negative poles of power to the negative poles of power, and then get to the circuits, called power parallels
The first is equal power; the second is the same internal resistance for each power source
Characteristics of combined power: access to larger currents, i. E., the currents of the outer circuits are equal to the sum of the currents that pass over the power
Mixed circuits
Definition: a combination of elements in a circuit called hybrid circuit
(a) calculation of mixed circuits: first the electrical resistance values of the components intermingled and connected, then the point resistance values of the circuits; and by the total electrical resistance values of the circuits and the end voltage of the circuits, the total currents of the circuits are calculated according to ommm's law; the currents and voltages of the components are calculated gradually on the basis of the fractional relationship of the components and the fractional relationship of the components.
